I never ran Mad Mage. I looked at it and it didn't appeal. I think you can run enjoyable megadungeons using 5E rules (in fact, I hope I do!) but this isn't really structured as a megadungeon - at least, not the type of megadungeon I'll enjoy running a campaign in!Dungeon of the Mad Mage disappointed me. None of the charm of the og product. It highlighted how 5e isn't that conducive to big dungeon play. There's a dozen megadungeons I'd run before Mad Mage.
I played ToA as a player. The final dungeon and the canyon around it was cool but the jungle hexcrawl part was whatever. Every thing since has seemed terrible. Modules written by committee. Ridiculous.
Yeah, Omu and the Tomb are what I like as well. The jungle hexcrawl I think is pretty terrible - but I have a lot of friends (experienced, published designers as well!) who have a great time with it. It's hard knowing how much gets fixed by the DM!
Cheers!